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Fix performance when using bidirectional iterators: don't use std::distance!

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[SVN r31531]
This commit is contained in:
John Maddock
2005-11-01 17:36:42 +00:00
parent fc4f4ade1a
commit fb8e0bcea3
1 changed files with 24 additions and 4 deletions
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28
include/boost/regex/v4/perl_matcher_common.hpp
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@ -682,12 +682,32 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_restart_continue()
template <class BidiIterator, class Allocator, class traits>
bool perl_matcher<BidiIterator, Allocator, traits>::match_backstep()
{
std::ptrdiff_t maxlen = ::boost::re_detail::distance(backstop, position);
if(maxlen < static_cast<const re_brace*>(pstate)->index)
return false;
std::advance(position, -static_cast<const re_brace*>(pstate)->index);
#ifdef BOOST_MSVC
#pragma warning(push)
#pragma warning(disable:4127)
#endif
if( ::boost::is_random_access_iterator<BidiIterator>::value)
{
std::ptrdiff_t maxlen = ::boost::re_detail::distance(backstop, position);
if(maxlen < static_cast<const re_brace*>(pstate)->index)
return false;
std::advance(position, -static_cast<const re_brace*>(pstate)->index);
}
else
{
int c = static_cast<const re_brace*>(pstate)->index;
while(c--)
{
if(position == backstop)
return false;
--position;
}
}
pstate = pstate->next.p;
return true;
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif
}
template <class BidiIterator, class Allocator, class traits>